Visualization of velocity and kinetic energy variations at the air-water interface during wave breaking

Abstract

This study examines turbulent, multiphase flow dynamics in the gas phase induced by wave breaking in coastal environments, focusing on void ratio quantification and its effects on flow characteristics, kinetic energy, and density-related energy transfer. The entrainment of air, bubble formation, and high-velocity gradients from breaking waves pose challenges for conventional flow measurements, while transient air–water interactions further complicate the analysis of gas-phase dynamics. To address these complexities, Particle Image Velocimetry (PIV) is employed to quantify gas-phase phenomena and velocity distributions under three distinct wave-breaking conditions relevant to offshore engineering. PIV enables detailed analysis of velocity fields at the water–air interface, capturing variations in kinetic energy and momentum in the surrounding air phase. Additionally, the study compares water and gas momentum distributions and investigates kinetic energy variations induced by wave impacts. The evolution of water–gas velocity fields is also analyzed across different wave-breaking types over an impermeable sloped bottom, providing insights into air–water interaction mechanisms in coastal hydrodynamics.